Zinc Coating Failure Analysis and Sheet Formability during Hot-Dip Galvanized Sheet Stamping

Abstract

By doing Erichsen experiments, samples of hot-dip galvanized sheet under different Erichsen depths (ED) were got. Surface and cross-section of these samples were analyzed by using SEM and EDS, which can show morphology and chemical composition respectively. Failure modes of galvanized sheet under different ED were researched. Then evolution process of zinc coating failure and effects of it on galvanized sheet formability were discussed. The results indicate that during hot-dip galvanized sheet stamping, zinc coating will pulverize, exfoliate and fracture for influence of friction and forming force, which leads to decrease of galvanized sheet formability.

The influence of pre-plating on the LME phenomenon of advanced high strength steel

“…The melted Zn appears to penetrate into the austenite grain boundaries causing an embrittlement characterized by surface crack formation under the influences of high temperature and complex stress, leading to the phase-transformation of austenite to ferrite [3]. The penetration of Zn is the main reason causing embrittlement, which called liquid metal embrittlement (LME) [4]. The brittle intermetallic compound ϒ phase Fe3Zn10 formed during the resistance spot welding is found to be the main reason for the LME.…”